196 
EXPLORATIONS IN TURKESTAN. 
lOi 
Vv^i^^l 
(6) Moraines of the Taka Valley. — Tlie last valle)- to be described, that of 
Taka Sii, on the north side of the Pamir, heads in two larj^je cirques on the north 
slope of the peak of Kliitai Saz, 17,500 feet high. The slope from here to the 
Alai basin is steep and the stream has been cutting steadily downward all through 
glacial times and to the present. The cutting has been most active in the soft 
Mesozoic-Tertiarv strata which lie between the basin and the mountains. As this 
is the place where most of the moraines were deposited, they too have been 
dissected; but fortunately none have been entirely destroyed, and the dissection 
furnishes a means of ascertaining what occurred during the interglacial epochs. 
The moraines number five, in addition to the one now in process of formation, and 
all are distinctly separated from their neighbors. We will take them up in order 
of age, beginning with the oldest. 
The first moraine is merely a covering of bowlders and finer glacial material 
lying on the hills east of the Taka Su, at an elevation of from 800 to 1,200 feet 
above the stream where it debouches on the plain 
of the Alai basin (fig. 138). The bowlders are 
chiefly limestone or calcareous slate of the com- 
mon Paleozoic type, and many are of large size 
and quite angiilar. The surface of the moraine 
is completely graded, and shows only a few 
traces of glacial topography, such as crooked 
drainage lines and a few detached hollows. The 
countr}- rock does not crop out through the 
moraine itself, but on the sides of the valley cut 
through the moraine the red beds of Mesozoic or 
Tertiary age, which extend all along the base of 
the mountains and must underlie the moraine, 
are seen up to an altitude of 600 feet above the 
stream. 
The ne.\t moraine is composed of the same 
materials as the first. It has clearly the morainal 
type of topography, although in a subdued and 
well-graded fonn. Its relation to the others is 
shown in the accomi>anying sketch map and 
cross-section (figs. 13.S and 139), where it is .seen 
Moraines of the Taka that the secoud moraine lies as a narrow terrace 
in the valley wliich was eroded on the western 
side of the first, about 400 feet above the stream. The first moraine was formed 
when the valley had been eroded to a depth much less than now and when 
the glacier was therefore free to spread over a considerable area. The second 
moraine was fonned when the relief was much more like that of to-day, and the 
glacier was closely hemmed in by a well-defined valley. It seems impossible to 
explain this relation except by supposing that after the first glacial epoch the ice 
retreated far upstream above the upper end of the terrace and staid there long 
■^\\x\\^:^x^ 
Uns:mdf<l areas represent gravel. i-5=old mo- 
raine; 6 =nio,1ern moraine ; 7 =b-cl rock. 
Fig. 138.-Pla 
of itie 
Valley. 
